/****************************************************************************
**
** Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of a Qt Solutions component.
**
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Solutions Commercial License Agreement provided
** with the Software or, alternatively, in accordance with the terms
** contained in a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** Please note Third Party Software included with Qt Solutions may impose
** additional restrictions and it is the user's responsibility to ensure
** that they have met the licensing requirements of the GPL, LGPL, or Qt
** Solutions Commercial license and the relevant license of the Third
** Party Software they are using.
**
** If you are unsure which license is appropriate for your use, please
** contact Nokia at qt-info@nokia.com.
**
****************************************************************************/


#include "qtlocalpeer.h"
#include <QtCore/QCoreApplication>
#include <QtCore/QTime>

#if defined(Q_OS_WIN)
#include <QtCore/QLibrary>
#include <QtCore/qt_windows.h>
typedef BOOL (WINAPI *PProcessIdToSessionId) (DWORD, DWORD *);
static PProcessIdToSessionId pProcessIdToSessionId = 0;
#endif
#if defined(Q_OS_UNIX)
#include <time.h>
#include <unistd.h>
#endif

namespace QtLP_Private {
#include "qtlockedfile.cpp"
#if defined(Q_OS_WIN)
#include "qtlockedfile_win.cpp"
#else
#include "qtlockedfile_unix.cpp"
#endif
}

const char *QtLocalPeer::ack = "ack";

QtLocalPeer::QtLocalPeer (QObject *parent, const QString &appId)
    : QObject (parent), id (appId) {
    QString prefix = id;

    if (id.isEmpty()) {
        id = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
        id = id.toLower();
#endif
        prefix = id.section (QLatin1Char ('/'), -1);
    }

    prefix.remove (QRegExp ("[^a-zA-Z]"));
    prefix.truncate (6);

    QByteArray idc = id.toUtf8();
    quint16 idNum = qChecksum (idc.constData(), idc.size());
    socketName = QLatin1String ("qtsingleapp-") + prefix
                 + QLatin1Char ('-') + QString::number (idNum, 16);

#if defined(Q_OS_WIN)

    if (!pProcessIdToSessionId) {
        QLibrary lib ("kernel32");
        pProcessIdToSessionId = (PProcessIdToSessionId)lib.resolve ("ProcessIdToSessionId");
    }

    if (pProcessIdToSessionId) {
        DWORD sessionId = 0;
        pProcessIdToSessionId (GetCurrentProcessId(), &sessionId);
        socketName += QLatin1Char ('-') + QString::number (sessionId, 16);
    }

#else
    socketName += QLatin1Char ('-') + QString::number (::getuid(), 16);
#endif

    server = new QLocalServer (this);
    QString lockName = QDir (QDir::tempPath()).absolutePath()
                       + QLatin1Char ('/') + socketName
                       + QLatin1String ("-lockfile");
    lockFile.setFileName (lockName);
    lockFile.open (QIODevice::ReadWrite);
}



bool QtLocalPeer::isClient() {
    if (lockFile.isLocked())
        return false;

    if (!lockFile.lock (QtLP_Private::QtLockedFile::WriteLock, false))
        return true;

    bool res = server->listen (socketName);
#if defined(Q_OS_UNIX) && (QT_VERSION >= QT_VERSION_CHECK(4,5,0))

    // ### Workaround
    if (!res && server->serverError() == QAbstractSocket::AddressInUseError) {
        QFile::remove (QDir::cleanPath (QDir::tempPath()) + QLatin1Char ('/') + socketName);
        res = server->listen (socketName);
    }

#endif

    if (!res)
        qWarning ("QtSingleCoreApplication: listen on local socket failed, %s", qPrintable (server->errorString()));

    QObject::connect (server, SIGNAL (newConnection()), SLOT (receiveConnection()));
    return false;
}


bool QtLocalPeer::sendMessage (const QString &message, int timeout) {
    if (!isClient())
        return false;

    QLocalSocket socket;
    bool connOk = false;

    for (int i = 0; i < 2; i++) {
        // Try twice, in case the other instance is just starting up
        socket.connectToServer (socketName);
        connOk = socket.waitForConnected (timeout / 2);

        if (connOk || i)
            break;

        int ms = 250;
#if defined(Q_OS_WIN)
        Sleep (DWORD (ms));
#else
        struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
        nanosleep (&ts, NULL);
#endif
    }

    if (!connOk)
        return false;

    QByteArray uMsg (message.toUtf8());
    QDataStream ds (&socket);
    ds.writeBytes (uMsg.constData(), uMsg.size());
    bool res = socket.waitForBytesWritten (timeout);
    res &= socket.waitForReadyRead (timeout);  // wait for ack
    res &= (socket.read (qstrlen (ack)) == ack);
    return res;
}


void QtLocalPeer::receiveConnection() {
    QLocalSocket *socket = server->nextPendingConnection();

    if (!socket)
        return;

    while (socket->bytesAvailable() < (int)sizeof (quint32))
        socket->waitForReadyRead();

    QDataStream ds (socket);
    QByteArray uMsg;
    quint32 remaining;
    ds >> remaining;
    uMsg.resize (remaining);
    int got = 0;
    char *uMsgBuf = uMsg.data();

    do {
        got = ds.readRawData (uMsgBuf, remaining);
        remaining -= got;
        uMsgBuf += got;
    }
    while (remaining && got >= 0 && socket->waitForReadyRead (2000));

    if (got < 0) {
        qWarning() << "QtLocalPeer: Message reception failed" << socket->errorString();
        delete socket;
        return;
    }

    QString message (QString::fromUtf8 (uMsg));
    socket->write (ack, qstrlen (ack));
    socket->waitForBytesWritten (1000);
    delete socket;
    emit messageReceived (message); //### (might take a long time to return)
}
